Determination of aquifer parameters using geoelectrical sounding and pumping test data in Khanewal District, Pakistan

In order to determine the groundwater resources and potentials of the Khanewal District of Pakistan, a geophysical method in combination with pumping test data were used. An analytical relationship between the aquifer parameters interpreted from surface geoelectrical method and pumping test was established in order to estimate aquifer parameters from surface measurements where no pumping tests exist. For the said purpose, 48 geoelectric investigations were carried out using Schlumberger vertical electrical sounding (VES). Seven of the soundings were conducted where pumping tests had been carried out at borehole sites. The vertical electrical sounding stations were interpreted, and resistivities and thickness parameters were calculated. The values of transmissivity and hydraulic conductivity were calculated using the Dar Zarrouk parameter. Transmissivity values obtained from pumping test data and the VES method range between 954 – 4263 m2/day and 200 – 5600 m2/day respectively. Hydraulic conductivity values determined from pumping test data and geoelectrical technique range between 15.9 – 60.9 m/day and 29.76 - 72.3 m/day respectively. The low values of transmissivity and hydraulic conductivity indicate clay or shale while high values are due to the presence of sand or gravel. A comparison of the transmissivity values obtained from pumping test data and surface geoelectrical method shows a positive correlation (R2 =0.90). Similarly, the regression between hydraulic conductivity determined from the pumping test data and the geoelectrical method is also positively correlated (R2 =0.96). The results provide a quick and useful estimation of aquifer properties and potentials